Yes, definitely can be cheaper, BUT! Kind of risky. If you book one ticket and your flight gets messed up, the airline(s) is still responsible for getting you there. If you book separate tickets and something happens, you could be SOL. Your outbound flight is delayed, and you are just a no-show on the second flight, and they don't have to accommodate you at all. Same on the way home. Generally not worth the risk to me. Your mileage may vary..